This can be taken to a bit of an extreme. Do you knap the flint, to dig the ore, to smelt the metal, to forge the plow, to grow the corn, to make the mash, to distill the drink ? At some point, a non-self-sufficient person provided the tools to allow you to live a self-sufficient life-style.

Many of the principles of self sufficiency are used in other movements such as homesteading, survivalism, simple living (or voluntary simplicity) , hobby farming, smallholding and off-grid living. All utilise some aspects of living solely on what you can produce yourself from your own piece of land. Since this is almost impossible to do entirely many choose to produce more than they need in food and other goods, which they can then barter with for other goods and services.

A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects. - Robert A. Heinlein

Specialization is the basis for much of human progress, and provides (for example) the tools mentioned above. Historically, when small communities of only a few thousand people became isolated, they actually lost skills as there weren't enough people to carry on the traditions of all the specializations. The Tasmanian AboriginesW are an example of this, after they were cut off from the Australian mainland.